The first one I used only lasted 30,000 miles before it was noticeably dirty throughout the inside of the flutes, but that's probably because of the polluted city environment my car was driven in. The Volant air filter did a great job in keeping the throttle body clean, better than the K&N reusable filter it replaced in the cold air intake system. When the Volant is new, it may provide a slight throttle-response and gas mileage advantage over other types of filters common to cold air intake systems, but when it starts to clog there'll be a noticeable drop in gas mileage and throttle response. When I replaced my dirty Volant with a clean one, the improvement in throttle response was instantaneous. This is an excellent air filter to use if you don't mind spending the money to replace it every 30,000 to 40,000 miles.